This invention relates to improvements in the design of an adiabatic condenser or fluid cooler. More specifically this details two new control modes; energy savings mode and water savings mode; which are designed to optimize the use of these resources based on cost and availability. This invention may be applied to units employing adiabatic saturation pads and also applied to units that employ any means to evaporate water (such as spray nozzles) before an indirect coil to reduce and cool the entering air temperature to the indirect coil.
Prior art adiabatic control systems use a combination of water and electrical energy to provide the necessary cooling required. Electrical energy is used to drive the fans, which moves air through the coil(s). Water is used to wet the adiabatic material and lower the temperature of the air passing through the coil. This prior art system saves energy over an air cooled system and saves water over an evaporative system by using the combination of resources. Typical prior art condensers or fluid coolers can switch from dry to wet operation at a certain preset outdoor temperature or preset temperature or pressure condition; however, the prior art systems do not allow the savings of either water or energy resource to be optimized.
This invention allows the system to reduce the usage of the customer chosen resource (either water or energy) to the minimum level possible while still meeting the cooling demand. The system will favor the resource, either energy or water, that is less costly or less scarce at a given time. For example, if energy is determined to be scarcer or more costly, the system will use water whenever possible to minimize energy use. If water is the scarcer or more costly resource, then the system will use water only when necessary to meet the heat rejection target.
This invention also includes multiple methods for switching between the modes of operation. Mode selection can occur manually by changing a setting in the controls or can also be automated to provide the lowest utility usage cost for the user. Utility rates for electricity and water can be provided either manually or automatically via communications. With this information, the controls can determine the mode of operation that provides the lowest cost of ownership to the customer.
Another method for switching between modes is to accept a peak demand signal from a utility provider. This signal may be manually input or automatically sent by the utility. When this signal is triggered, it would cause the unit to favor the resource that is not currently in peak demand (typically electrical energy). This method of control would help to conserve scarce regional resources as well as reducing peak demand charges for the user.
For units employing adiabatic saturation cooler pads, this invention also includes the ability to increase the airflow through the coil when operating “dry”. When running in the dry mode, the prior art product has a penalty of pressure drop through the adiabatic pads and consequently having reduced airflow through the unit. By bypassing air flow around the pads during dry operation, more airflow may be achieved thereby reducing fan motor energy usage and allows more conserving of water for longer periods of time.
Another feature of this invention is a coil cleaning program. This feature runs the fans backwards to force air through the coil in the opposite direction to force dirt and other debris out of the coil fins to improve the efficiency of the coil. This coil cleaning feature can be combined with a spray system on the coil to improve the cleaning. It can also be combined with the air bypass system so that any material blown out of the coil is blown clear of the unit. The pads could also be wet during cleaning mode to rinse debris that comes off the coil down into the sump other than onto the ground.